Centerless grinding machine



Nov. 15, 1955 Filed July 6, 1953 E. L. DIX

CENTERLESS GRINDING MACHINE 2 Sheets-Sheet l NOV. 15, 1955 x CENTERLESS GRINDING MACHINE 2 Sheets-Sheet 2 Filed July 6, 1955 jaw/2751" ZMar J United States Patent Office 2,723,499 Patented Nov. 15, 1955 CENTERLESS GRINDING MACHINE Edward L. Dix, Chester, Vt., assignor to Bryant Chucking Grinder Company, Springfield, Vt., a corporation of Vermont Application July 6, 1953, Serial N 0. 366,217

7 Claims. (CI. 51-48) This invention relates to centerless grinding machines for grinding the internal surface concentric with the external surface on an annular workpiece, for example, a ball bearing ring. The workpiece is supported by shoes engaging the external surface. Such a machine is described in Arms and Grobey U. S. Patent No. 2,635,395 to which reference can be had. As disclosed in that patent, the workpiece to be worked on is supported on shoes in eccentric relationship to the com mon axis of the work driving spindle and a cooperating face of a supporting and clamping means. This arrangement is satisfactory in many cases. However, when gaging means of the kind described in Ljunggren U. S. Patent No. 2,502,862, arranged substantially concentric with the workpiece, is used complications arise and an object of this invention is to overcome such complications.

A further object of this invention is to arrange the work supporting elements in such a way that a stable condition always prevails for the workpiece whether the work is rotated idly or when the tool aids the forces exerted on the work.

Still a further object is to use simple and uncomplicated means allowing for greatestflexibility and ease of adjustment when changing from one size of work to another.

In Arms and Grobey U. S. Patent No. 2,653,395, the workpiece is held in eccentric relationship to the driving and axially supporting and clamping means. If now gaging means as described in Ljunggren U. S. Patent No. 2,502,862 be applied to such a machine, a complex mechanism would be necessary to offset the sensing gage head eccentric from its supporting and translating means which have to beconcentricwith the work driving spindle. Although such a mechanism is in realm of possibility it would be detrimental in a device as this whether accuracy and stability is a prerequisite and, therefore, simplicity and elimination of possibility for lost motion seem to require a different solution.

The present invention meets such prerequisite by supporting the workpiece concentric with the driver spindle and thereby in concentric relationship with the. gaging means, and novel means are provided to hold the workpiece against the radially supporting means.

The present invention provides a simple and effective means acting to hold the workpiece against the face of the driver spindle and against radially supporting shoes in a manner to produce a stable condition on-the workpiece either when it is running idle or when the tool exerts a force thereon.

For this purpose an axially clamping device is arranged ofi'set in eccentric relationship to the driver spindle and with the work piece supported concentric with the spindle. The eccentricity of said clamping device or means is so chosen as to effect a stable running condition as will be clearvfromthefollowing description.

For a complete understanding of this invention, reference may be had to the accompanying drawings in which Figure 1 is a view partly in side elevation and partly broken away and in central longitudinal section of a grinding wheel head and related parts arranged for centerless internal grinding in accordance with this invention.

Figures 2 and 3 are detail sectional views on lines 22 and 3-3, respectively, of Figure 1.

Figure 4 is a somewhat diagrammatic view showing the eccentric relations between the clamping plate and the work piece and spindle and the proper relations between the grinding wheel and the work.

Referring to the drawings, and first more particularly to Figure 1, at 1 is shown a rotary spindle mounted in suitable antifriction bearings 2 in a work head 3. The rear end of the spindle 1 has means by which it may be rotated as, for example, a belt pulley 4. The forward end of the spindle is provided with a standard spindle nose against which may be secured a face plate comprising an annular member 5 having a rear face shaped to engage and be secured to the spindle nose. An annular member 6 projects forwardly from the member 5 and has at its forward end a spacer ring 7 presenting a face transverse to the axis of the spindle against which the work piece 8 may be pressed.

This face plate and the spindle are intended to have pressed thereagainst and coaxially therewith the work piece 8, and this pressing is done by an annular clamping plate 10 having a pressure ring 11 on its back face which is pressed against the outer face of the work piece 8 and engages it on opposite sides of its rotational axis. Such pressure may be exerted by fluid pressure, as, for example, compressed air, for which purpose the outer face of the clamping plate 10 is formed with concentric ribs 12, 13 and 14 with which cooperate similar annular ribs 15, 16 and 17 of a fixed annular plate 18. These ribs which nest relative to each other provides a labyrinth packing between the stationary plate 18 and the clamping ring 10, and between which air under pressure may be admitted as through the pipe 20, radial passage 21, and annular passage 22, and a series of ports 23 leading from the passage 22 into a narrow passage 24 between the ring 18 and the clamping ring 10. This air presses the clamp ring 10 rearwardly which clamps the work piece against the face plate members.

The clamping ring, instead of being concentric with the spindle, is slightly eccentric, the amount of eccentricity being shown much exaggerated in Figure 4. This eccentricity is so related to the axis of the spindle 1 as to cause by rotation of the spindle, and with it the clamping ring 10, a component of force laterally of the face plate and the axis of the spindle which presses the outer face of the work piece 8 against antifriction balls 25 carried at the ends of a pair of shoes 26 and 27. These shoes are adjustably secured to a stationary annular member 28 which is secured to an annular stationary bearing member 30 which has a flanged portion 31 surrounding the rotary spindle nose at the outer end of the spindle 1. The balls 25 are arranged to engage a peripheral groove 35 in the outer finished face of the work piece 8, and the two balls are located at opposite endsof an arc of substantial angular extent.

The shoes 26 and 27 are adjustable radially, being mounted in radial grooves 36 in the ring member 28 wherein they may be clamped, as by clamping screws 37, threaded into the stationary member 28 and passing through enlarged openings 38 in the shoes. An adjusting screw 39 threaded. through a transverse member 40 and having a lock nut 41 thereon serves to adjust the shoes radially, and such adjustment is made until the work piece rotates as near as possible concentric with the spindle 1. The eccentricity of the clamping plate need be only slight, but it must be in the proper direction to produce a thrust on the work lying within its arc of support on the shoes 26 and 27.

A grinding wheel 56) arranged on an arbor 51 and rotarily carried by a wheel head 53 is arranged to pass through the central aperture of the clamping ring and engage with the inner face of the work piece 8, thereby to grind a hole through this work piece with its inner periphery in substantial parallelism with the external finished face of the work piece. This grinding wheel 50 may becaused to enter the hole in the work and when so entered may be reciprocated and fed against the side of the hole in the work by any suitable means not material to this invention.

Since the work piece is clamped concentric with the spindle, it is an easy matter to associate therewith an automatic size gage. As shown, this size gage55 is of the plug type which may be moved periodically axially toward and from the work, as is well known in the art, when the desired work size is being approached, the work being of the correct internal size as soon as it permits the gage 55 to enter into the hole. To the gage 55 may be secured a shaft 6i) movable axially through a packing 61, for this purpose. By careful adjustment of the shoes 26 and 27, it is possible to support each work piece so near concentricity with the spindle that the use of an automatic size gage as disclosed is entirely feasible.

In Figure 3 there is also shown a hopper 65 by which work pieces may be fed into position as required between the face plate and the clamping ring and properly engaging the shoes 27 with their ball ends 25. Any suitable means may be provided for feeding work pieces to the machine to be ground and then for removing them from the machine after grinding has been effected. One such means is shown in Figure 3 in which a slide 70 is mounted in guides 75 to pass across the forward face of the disk 28. This slide 79 has a cut away portion 71 so arranged as to clear a work piece positioned for the grinding operation. This slide 76? is provided with a push bar 72 secured to the member 70 as by the screws at 73. The slide 70 is also provided With a stop block 7- which can be pushed back and forth beneath the lowest work piece in the chute 65.

When the slide 70 is moved toward the right as viewed in Figure 3, this member 74 lifts the lowest work piece in the chute. At the same time through the rocking of a link 76 fulcrumed at 77 and having its lower end connected by a pin and slot connection at 78 with the slide 70, a work piece separator bar 7fi is pulled outwardly, removing its conical point 80 from between the lowest work piece W and the next one above it in the chute 65, allowing the upper of these work pieces to engage the lower work piece while relieving the work piece in grinding position from any extraneous forces.

When the slide 70 is moved toward the left as viewed in Figure 3, the stop 74 is withdrawn from beneath the lowest article in the chute and the divider pin 80 is projected, lifting the next to the lowest work piece out of contact with the lowest piece. At the same time the bar 72 acts on the work piece in position between the face plate and the clamping plate to roll it out into the upper end of a chute 81 from which articles may be taken from time to time as desired.

From the foregoing description of an embodiment of this invention it will be evident to those skilled in the art that various changes and modifications may be made without departing from its spirit or scope.

I claim:

1. In combination with a rotary spindle having a face plate at one end presenting a face transverse to the axis of rotation of said spindle and against which a work piece may be clamped, work supporting means positioned adjacent to said face and engageable with a finished external periphery of a work piece and located to support said work piece through a substantial circumferential are concentric with said spindle, and a work clamp engageable with the opposite face of the work piece from said face plate on opposite sides of its axis and movable lengthwise of said axis to clamp to and release the work piece from said face plate, said clamp being journaled for rotation with said spindle about an axis eccentric to said spindle axis, said eccentricity being disposed in direction to cause the rotation of said clamp with said spindle to produce a component of pressure on the work piece lying through and against said supporting arc to thereby press the work piece against said work supporting means as said spindle is rotated.

2. In combination with a rotary spindle having a face plate at one end presenting a face transverse to the axis of rotation of said spindle and against which a work piece may be clamped, work supporting means positioned adjacent to said face and engageable with a finished external periphery of a work piece and located to support said work piece through a substantial circumferential arc concentric with said spindle, a work clamp engageable with the opposite face of the work piece from said face plate and movable lengthwise of said axis to clamp to and release the work piece from said face plate, said clamp being journaled for rotation with said spindle about an axis eccentric to said spindle axis, said eccentricity being disposed in direction to cause the rotation of said clamp with said spindle to produce a component of pressure on the work piece lying through and against said supporting arc to thereby press the work piece against said work supporting means as said spindle is rotated, said clamp having a central aperture therethrough, and a tool mounted for motion through said aperture and into operative relation to an internal surface of the work piece.

3. In combination with a rotary spindle having a face plate at one end presenting a face transverse to the axis of rotation of said spindle and against which a work piece may be clamped, work supporting means positioned adjacent to said face and engageable with a finished external periphery of a work piece and located to support said work piece through a substantial circumferential arc concentric with said spindle, a work clamp engageable with the opposite face of the work piece from said face plate on opposite sides of its axis and movable lengthwise of said axis to clamp to and release the work piece from said face plate, said clamp being journaled for rotation with said spindle about an axis eccentric to said spindle axis, said eccentricity being disposed in direction to cause the rotation of said clamp with said spindle to produce a component of pressure on the work piece 1ying through and against said supporting arc to thereby press the Work piece against said work supporting means as said spindle is rotated, means for operating on an internal surface of the work piece so clamped to cut said surface concentric with said finished surface, and a size gage carried by said spindle and movable into and out of the work piece and arranged to gage the diameter of said internal surface.

4. In combination with a rotary spindle having a face plate at one end presenting a face transverse to the axis of rotation of said spindle and against which a work piece may be clamped, work supporting means positioned adjacent to said face and engageable with a finished external periphery of a work piece and located to support said work piece through a substantial circumferential are concentric with said spindle, a work clamp engageable with the opposite face of the work piece from said face plate and movable lengthwise of said axis to clamp to and release the work piece from said face plate, said clamp being journaled for rotation with said spindle about an axis eccentric to said spindle axis, said eccentricity being disposed in direction to cause the rotation of said clamp with said spindle to produce a component of pressure on the work piece lying through and against said supporting are to thereby press the work piece against said work supporting means as said spindle is rotated, said clamp and spindle having central apertures therethrough, a grinding wheel mounted for motion through one of said apertures into contact with an interior surface of the work piece so supported, and a size gage mounted for motion through the other of said apertures into gaging relation to said interior surface.

5. In combination with a rotary spindle having a face plate at one end presenting a face transverse to the axis of roation of said spindle and against which a work piece may be clamped, work supporting means positioned adjacent to said face and engageable with a finished external periphery of a work piece and located to support said work piece through a substantial circumferential arc concentric with said spindle, and a work clamp engageable with the opposite face of the work piece from said face plate on opposite sides of its axis and movable lengthwise of said axis to clamp to and release the work piece from said face plate, said clamp being journaled for rotation with said spindle about an axis eccentric to said spindle axis, said eccentricity being disposed in direction to cause the rotation of said clamp with said spindle to produce a component of pressure on the work piece lying through and against said supporting arc to thereby press the work piece against said work supporting means as said spindle is rotated, said work supporting means comprising a pair of work piece engaging shoes for engag ing the work piece at opposite ends of said supporting are.

6. In combination with a rotary spindle having a face plate at one end presenting a face transverse to the axis of rotation of said spindle and against which a work piece may be clamped, work supporting means positioned adjacent to said face and engageable with a finished external periphery of a work piece and located to support said work piece through a substantial circumferential arc concentric with said spindle, a work clamp engageable with the opposite face of the work piece from said face plate and movable lengthwise of said axis to clamp to and release the work piece from said face plate, said clamp being journaled for rotation with said spindle about an axis eccentric to said spindle axis, said eccentricity being disposed in direction to cause the rotation of said clamp with said spindle to produce a component of pressure on the work piece lying through and against said supporting arc to thereby press the work piece against said work supporting means as said spindle is rotated, and said supporting means comprising a pair of shoes each having a ball journaled therein for engaging in a groove in said finished periphery at opposite ends of said arc.

7. In combination with a rotary spindle having a face plate at one end presenting a face transverse to the axis of rotation of said spindle and against which a work piece may be clamped, work supporting means positioned adjacent to said face and engageable with a finished external periphery of a work piece and located to support said work piece through a substantial circumferential arc concentric with said spindle, a work clamp engageable with the opposite face of the work piece from said face plate and movable lengthwise of said axis to clamp to and release the work piece from said face plate, said clamp being journaled for rotation with said spindle about an axis eccentric to said spindle axis, said eccentricity being disposed in direction to cause the rotation of said clamp with said spindle to produce a component of pressure on the work piece lying through and against said supporting arc to thereby press the work piece against said work supporting means as said spindle is rotated, said clamp having a central aperture therethrough, a rotary grinding wheel mounted for motion through said aperture and into operative relation to an internal surface of the work piece, the engagement of said wheel on the work piece and its direction of rotation being such as to exert a pressure component on the work piece against said work supporting means.

References Cited in the file of this patent UNITED STATES PATENTS 469,910 Edwards Mar. 1, 1892 2,635,395 Arms Apr. 21, 1953 2,646,652 Blood July 28. 1953 

